Interestingly with all the issues people have with the original MUF Delta shape it still is the fastest fin at Budgie holding the 2 second record. The Delta XT has yet to be used in record breaking conditions but I think it will be able to go faster at budgie as you will be able to use a smaller fin say a 14 instead of a 16 thus reducing the about of resistance caused by weed and allowing access to very shallow sections for those that dare.

Warning: yet another soapbox nerdy rant ahead!
Bottom growing weed has the effect of increasing the 'dynamic viscosity' of the water. This in turn will decrease the Reynolds number and increases the Ncrit. Laminar flows last longer. Laminar flows produce higher lift for less drag. Laminar flows are *generally a happy place for fins to be. All high rake fins will benefit from this water state and perform far better than in turbulent water. The drag becomes the dominant factor and the rake and effective length of the leading edge being the biggest contributor. So if your local strip allows you to sail in smooth water the whole time, go for the shortest fin that provides the lift you require and that you are confident using.
( * I am not aware of any supercavitating design for shallow weedy water)

BUT, if your speed strip requires sailing in choppy water, especially upwind work, the above situation reverses. You will now be faced with low Ncrit and high Reynolds numbers. This is the time when your fin's ability to deal with these conditions becomes very important, as all these two factors are pertubating. Your fin must now deal with turbulent flows AND produce enough lift to resist sail load and to point upwind.

As you have probably guessed, this is when the comprises in fin design to decrease drag in shallow weedy water come home to roost. Whether those compromises are acceptable depends on the sailor. For the 'no compromises' sailor, a low drag short fin will be diabolical for upwind work in chop, but once you finally make it to the top of your speed run, and the holes in the cheese align, you will reap the rewards of the lowest drag and a high speed run.

For the average sailor, some degree of compromise between lift and drag will put more grins on the dial as we don't all have the same skills/strengths sailing. So for me, it's defo a 'horses for courses' scenario, with not only, no two speed courses being the same, but not everyone's expectations of a great day on the water being the same either. Finally, before I climb down from my soapbox and finish this little rant, it has been calculated that once the board is planing the fin is approximately 15% of total drag. Most of the drag is you and the sail, and then your board. Pick on those before blaming your fin for low speeds :-)

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fangman said..
Sailquik's comments do not apply to Fangy's at the moment.The only successful Delta's are these:





View from The Hook Par 5 should clear up any confusion.

And I thought Budgy was thick..

I can sort of follow Fangy's theory explanation as Im not real bright. Its obvious that we all sail in different weed/depth conditions but the number of different fin shapes and profiles is quite large. Horses for courses, if it works for you it probably wont for someone else. I sail at Budgey a lot for a non local and have tried several different rakes, depth, and plan shapes. Some work, some don't. Some work on days when the weed isn't scary and bus size and its easy to go through. Then lately its been super thick and for the first time Ive tried a Delta just for the rake so I don't kill myself. I have a hand shaped fin of the same rake but its for bigger gear. I was pleasantly surprised. I then borrowed a smaller Delta from Millsy on a strong day and it was fine. I havent tried the 2 fins that are up for discussion so cant comment. But all the boys say they love them so who knows?? Try and ye shall discover what works for you.

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ka43 said..
..................... Try and ye shall discover what works for you.

Wise words Obe Kenobe!

If any one wants to try a kestral all they have to do is ask and i am sure we can organise something , as stated before all the fins work you just gotta have a go and see what suits you and than stick with it and the rewards will come

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Stretchy said..
Hmmm, I think weed is biggest factor for Fangy's and Liptons, so WS50 probably best option, particularly if mixed with a bit of chop. Thanks for the photo

I bit the bullet, this arrived in the mail today. Can't wait to try it out
thanks for the advice Sailquik

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Stretchy said..

Stretchy said..
Hmmm, I think weed is biggest factor for Fangy's and Liptons, so WS50 probably best option, particularly if mixed with a bit of chop. Thanks for the photo

I bit the bullet, this arrived in the mail today. Can't wait to try it out
thanks for the advice Sailquik

Stretch, what fin were you using on the weekend for your 200? You had plenty of speed then, any weed issues? Hit the bottom?
I was on Tribal SW25 and only had issues when i didn't gybe well and then caught the weed, I did feel the bergs too.

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BSN101 said..

Stretchy said..

Stretchy said..
Hmmm, I think weed is biggest factor for Fangy's and Liptons, so WS50 probably best option, particularly if mixed with a bit of chop. Thanks for the photo

I bit the bullet, this arrived in the mail today. Can't wait to try it out
thanks for the advice Sailquik

Stretch, what fin were you using on the weekend for your 200? You had plenty of speed then, any weed issues? Hit the bottom?
I was on Tribal SW25 and only had issues when i didn't gybe well and then caught the weed, I did feel the bergs too.

Hi Dave. I was using a MUF Delta 19. Probably overkill as plenty others were using conventional weedies. Then again, I had no problems gybing or through bergs and It did give me more freedom as to where I could sail. The new MUF XT would have worked better I reckon, or a bit bigger version of my new BP

I have a 20cms BP50 weedspeed that I love and use in slightly deeper choppy water at Budgy ( NE direction). I don't usually aim it at the thickest weed as I feel a little bit of a tug hitting those..I haven't really tried it in the thick stuff.
It hangs in great and I can push on it ( unlike a delta).
I just tried the 16 kestrel for the first time yesterday ( they don't make the BP50's in less than 20cm deep). Very impressed. I did find out you should check for weedbergs before you gybe.. ( it's been 4 months since I sailed the really thick stuff). No fin would cope with a large dry weedberg. . The kestrels hung on great in the small chop and ripped through the thick weed upwind and on the bearaways.
I was so impressed I got overconfident coming back across the channel well powered in 1- 11/2 ft chop and didn't allow for the fact that it was a 16cm fin with a 6.2m sail so I spunout and fell in and then once I got going again I went sideways all the way back in.. I was very tired so I didn't even try and straighten out of it.
The 16cms was great and I did bearaways right through the shallows on a few runs ( brown pants stuff waiting on hitting bottom and going over the front but I didn't).
Tibor took a great pic of a a delta , Kestrel and delta Xt laid over each other to show the comparative angles..I'll see if I can upload a pic via my phone..

Comparative pic..
All 16cms - bottom one normal delta - blk one is a kestrel - top is the delta XT

Very interesting comparison photo. Well done and thanks for posting.

+1 ^. Nice photo Sue - can you please ping one off in reverse order so we can compare the surface area of the fins on the trailing edge too?

Fangy I don't have a Kestrel but 19cm Delta v 18cm XT from the reverse side

Cheers for that Morts. I wonder if the total surface area of the two fins are similar: what is lost from on the front of the XT subtracted to what's added on the back of the XT = the old style Delta surface area of the same size fin.??

I thought of that later.. It was a combination of my fin and Tibor's two fins so I'll have to wait till next time to get a photo from the other side.

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fangman said..
Cheers for that Morts. I wonder if the total surface area of the two fins are similar: what is lost from on the front of the XT subtracted to what's added on the back of the XT = the old style Delta surface area of the same size fin.??

My comparisons of the standard MUF Delta and The XT lead me to thing that in the same size fin they have roughly the same surface area as you say what has been cut off the front has been put on the back. However I feel one of the main reasons the Delta XT handles the chop better is that it has a lot more surface area at the top so as you bounce over the chop more fin stays in the water on a XT than on standard Delta which quickly looses surface area as you reach the tip. This extra grip seem to allow those using the XT to use a fin 2-3cm smaller than they would use in a standard delta. Which is were the XT really helps out in shallow water as you can get in and out of the really shallow stuff.

Thanks Legless.

And the XT has a lot less rake, this also makes it better in chop.

Just heard that MUF is going to be making the Delta-XT from 10cm!!!! in 2 cm steps (10 cm, 12, 14, 16 .......26 cm)

It will be interesting to see what a 10cm Delta XT will do!